Norman Doidge, pioneer of neuroplasticity and author of The Brain’s Way of Healing: ‘I still have to pinch myself about what is possible.’ Photograph: Felix Clay

My walking companion, John Pepper, was diagnosed with Parkinson’s disease, a movement disorder, over two decades ago. He first started getting symptoms nearly 50 years ago. But unless you are a perceptive and well-trained observer you would never know he has the disease. He doesn’t appear to have the classic symptoms of the Parkinson’s patient: no shuffling gait, no visible tremor when he pauses or when he moves; he does not appear especially rigid and seems able to initiate new movements fairly quickly; he has a good sense of balance. He even swings his arms when he walks. He hasn’t been on anti-Parkinson’s medication for nine years, since he was 68 years old, yet appears to walk perfectly normally.

His recovery began in 1998. Understand that typical modern walking is a kind of controlled fall forward. What keeps us from falling over is that our feet support our weight first on one side, then the other. But Pepper discovered that when he walked, his weight was never well supported on the ball of his left foot, so he didn’t dare lift his right leg enough, and that he tended to drag his right foot. He observed that his left foot had no spring to it and he was not pushing up and forward on it. His left heel was still touching the ground when his right touched down. His right foot didn’t always clear the ground as it passed his left leg, giving rise to his shuffle. If the right foot did clear the ground, he could never straighten his rigid right knee fast enough, so that his right foot landed heavily because his body wasn’t sufficiently supported by his left foot. These were just the most obvious of the many subtle observations he made as to why he could not experience the controlled fall his walking should have been.

John Pepper Photograph: PR

It took him three months to get his left foot to support his full body weight. If he concentrated on supporting his body weight on his left foot, he was no longer in an uncontrolled fall and his right knee had time to straighten out before the heel touched the ground. Such attention required an extremely focused, almost meditative concentration, as when a child learns to walk for the first time or when a student does the slow-motion walking of tai-chi, which teaches more perfect movement by slowing things down.

His close observation exposed all the other problems of his gait. It took him a year of practice to internalise all these changes. His walking normalised – as long as he paid attention and concentrated on each action. Now that he was walking he could benefit from the fact that walking is “neuroprotective” because it triggers brain growth factors, and some new cells, in the brain.

When I walk with Pepper, I marvel that he can hold all these movements in his head. He insists he can, and because neither of us can bear to walk in silence, we talk as we go, and I observe how he can do two things at once; he can keep up the motor movements that the rest of us perform automatically, by using his conscious mind, and still have mental space left over for conversation. But as conversation deepens – when I ask him something that intrigues him, or that stumps him, or when he sees a bird he can’t identify, I can hear a foot drag, reminding us both he still has Parkinson’s; it’s just he has found a way to overcome it.

After mastering walking, Pepper began to take conscious control over his tremor. All his new techniques he realised involved “using a different part of my brain to control an action, which was normally controlled by my unconscious.” In practice this meant consciously performing tasks in slightly different ways than he had originally learned them. Likely this approach helped because it did not engage the brain areas that processed his existing unconscious programmes – the basal ganglia – which seemed the source of the trouble.

The smallest actions once stymied him, but soon he no longer needed his wife, Shirley, to help him button and unbutton his shirts. In his work for a Parkinson’s support group he helped a woman who had a terrible tremor when she brought a glass up to her lips approach the glass from behind consciously, instead of automatically from the side, as she normally did. Her tremor disappeared. Pepper took to holding his own fork at 45 degrees and grasping his spoon very lightly. Eating with Pepper you would never recognise he had Parkinson’s, except that his hands take odd paths to bring his food to his mouth, and he occasionally knocks something over when he becomes animated.

Over lunch at the Cape I heard Shirley cry, “John, watch it.”

“It’s OK, love,” he told her. “Shirley is always moving things out of my reach,” he said to me, “because when I reach subconsciously, I’ll knock a glass of wine with my hand. It goes on mostly when I should be concentrating. If I’m not, I’m always pulling wine back on to me because I don’t let go of it” – one of his original Parkinson’s symptoms.

But then I heard a loud “Ow!” as he was explaining this very point. “I just bit into my cheek.” He explained that it happens all the time, particularly if he doesn’t concentrate on chewing and swallowing.